[SAT课外阅读26]科学：How to make zoologists more productive

Time and motion study

How to make zoologists more productive

Source：The Economist, May 7,

Hang a collar fitted with a GPS tracker and a radio transmitter around a wild animal’s neck, or simply glue such a device to its back, and you will know all the time where it is. You will not, though, knowwhat it is up to—which is usually more interesting than its mere location. For this, you need to have someone in the field, watching and taking notes. That is expensive, needs special equipment to do at night and is impossible if the animal is underground in a burrow. But a group of ecologists and engineers at the University of California, Berkeley, led by Talisin Hammond, hope to change this state of affairs. As they describe in Experimental Biology, by adding an accelerometer to the tracker they have found a way to spy in detail on the lives of the world’sfauna.

Building the new tracker wasno mean feat. Ms Hammond studies chipmunks— animals that weigh about 35 grams. Anything such an animal is forced to carry around needs to be considerably lighter than this. Her colleague Dwight Springthorpe succeeded, however, in cramming the necessary processing chip and memory chip, accelerometer and lithium-polymer battery into a small weatherproof case, to produce a pack that weighed a mere 11⁄2 grams—or 4.25% of an average chipmunk’s body weight. The result was something that could be glued onto the back of a chipmunk with the sort ofadhesiveused to attach false eyelashes.

A battery light enough to be part of such a package cannot, of course, store muchjuice, so the researchers programmed the tracker to run for ten seconds every quarter of an hour, in order to sample the animal’s behaviour at regular and reasonably frequent intervals withouttaxingthe power supply too much. On thisregimeit lasted 41⁄2 days beforeconkingout.

The team’s first task was to understand which patterns of accelerometer behaviour corresponded to which patterns of animal behaviour. To find out, they tested the new device on 18 captive chipmunks, using video cameras to record the animals’ behaviour. When each recordingsessionwas over, they removed the tracker, downloaded the >up to, into a machine-learning algorithm designed by a third member of the team, Taylor Berg-Kirkpatrick. The algorithm proved a fast learner. Afterparsing28 hours’ worth of data from the captive chipmunks, it was able to work out what the rodents wereup to—running, grooming, digging, eating or lying still—82% of the time. Ms Hammond therefore put it to the test in the wild.

She and her colleagues attached the new trackers to 15 alpine chipmunks and 15 lodgepole chipmunks living in Yosemite national park, and then attempted tolivetrapthe animals between two and six days later. Nine of the alpines and 11 of the lodgepolesobligedthem by going into the traps, so they got 20 of their devices back.

Ms Hammond was not just collecting data at random. She was testing a hypothesis that alpine chipmunks would be more active than lodgepoles during mornings and evenings, and less so during the middle of the day. She suspected this because the alpine chipmunk’srangehas shifted more in response to global warming than has the lodgepole’s, leading her to wonder if it is more sensitive to heat, and thus more likely to becrepuscular.

As it turned out, her hypothesis was wrong. But she had been able todemonstrateits wrongness in two weeks of observation (one in the summer and one in the winter). A conventional study using field glasses and eyeballs would have taken ten times as long to gather enough data to draw an equivalent conclusion. That is a huge efficiency gain. Technology can improve productivity almost anywhere. Even, it seems, in zoology.

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Task 1: find out the exact meaning of each word in bold.

Task 2: summarize the main idea of each paragraph.